Solar sails are one of those things that a lot of people have heard about but no one really seems to know too much about. I guess I owe George Lucas and James Cameron a debt of gratitude for this phenomenon as both their sci-fi block busters feature the technology in one way or another. Still for all the postulating that has been done in the world of sci-fi that appears to well grounded in real world science you’d be hard pressed to actually find any actual craft that have launched and demonstrated the feasibility of solar sail technology. It would seem that something akin to the Mars Curse plagues the potentially revolutionary space propulsion that is solar sails.
That’s not for lack of trying however and since the idea was first thought of way 1924 by Friedrich Zander there have been many attempts to prove that the concept works. For a solar sail to work it needs a large surface area to capture as much of the minute pressure that the sun exerts on everything around it. This poses a significant challenge to craft designers as anything large either means lots of mass or some kind of tricky deployment system. As with any space mission weight is at a premium so all solar sails to date have been extremely large and very thin (in the order of millionths of a meter) and therefore have some kind of complicated deployment mechanism. As anyone who has worked with aluminium foil (which by comparison is 0.2mm thick, almost 100,000 thicker ) before can attest such materials are inherently fragile and all successful solar sail missions so far have focused on actually getting themselves deployed, not on whether or not solar sails actually work.
That might seem a bit strange, especially considering the potential game changer that solar sails are, but it all comes down to its potential applications. Right now there’s really little commercial interest outside Low Earth Orbit and as such the only interest comes from potential scienctifical applications. With the technology as of yet still unproven solar sails won’t make it aboard any deep space missions just yet as there can be no guarantee that it will function as predicted. This hasn’t stopped people from looking into the technology though, with Japan being the latest nation to step up to the plate:
Though solar sail-powered crafts have been used before, Ikaros is the first to attempt to enter deep space. The craft’s 46-foot sails come equipped with solar cells thinner than a human hair. When solar particles hit the cells, they generate power for Ikaros. Mission controllers on the ground will steer the craft by adjusting the sails’ angles, ensuring optimal amounts of radiation are reaching the solar cells.
Ikaros’s pricetag is in the realm of $16 million dollars. And while it’s certainly an ambitious project, there are no guarantees the fuel-free space explorer will work. A rocket will transport Ikaros to space on May 18th, along with Japan’s first satellite to Venus. Stay tuned to see how Ikaros fares when the spacecraft finally gets its day in the sun.
IKAROS (ha! Science humour) is quite interesting for a number reasons. The first is that it is the first solar sail mission to be aimed squarely at deep space. It’s admirable because nearly every other mission thus far hasn’t given any thought to get past LEO or HEO, mostly because it would be easier and cheaper. Secondly they’ve taken the novel approach of converting sections of the sail into solar panels as well, which will provide a decent amount of juice for the craft. This further reduces the required weight of the craft (eliminating heavy batteries) which means they can cram a whole lot more science into this package. Secondly the entire project is being funded on what is to be considered a shoestring, a mere $16 million dollars. If this project is successful it will not only prove that solar sails are a viable propulsion method it will also show that they can be extremely cheap. There are countless deep space missions that could be achieved if such deep space propulsion was this cheap, so you can see why the space community is a buzz with excitement at this missions prospects.
Solar sails are one of those technologies that’s been firmly rooted in the world of sci-fi for decades and the prospect of them becoming real just gets me all kinds of excited. I feel that we’re all extremely fortunate to be on the cusp on the next revolution in human’s ability to travel to places we’ve never gone before. The day will come when humanity begins stretching our reach beyond our solar system and there would be nothing more amazing than to do that by sailing on the solar pressure waves of our very own star.